SEA-UKOHINS AND SEA-CUCUMBEEB. 



3i1 



moreover, studded with those minute and glandular 

 specks, with which every part of the adult Urehia is 

 covered ; and the light is reflected from the various 

 prominences with sparkling brilliancy. 



The little creature moves through the water with 

 much grace, and with a dignified dehberation ; the 

 crest being always uppermost, and the perpendicular 

 position invariably maiataiaed. It does not appear 

 capable of resting, its movements depending on inces- 

 santly vibrating cilia. These organs we perceive 

 densely clothing the long ear-pieces, but more espe- 

 cially accimiulated and more vigorous in a thickened, 

 fleshy band, which passes partly round the whole hel- 

 met, at the origin of these pieces. 



Ton do not discern the slightest resemblance of 

 form between this little slowly-swimming dome and 

 the spined and boxed Urchin which 

 crawls over the rocks ; and you won- 

 der by what steps the tiny atom of 

 one-fortieth of an inch in length is led 

 to its adult stage. Fortunately I can 

 satisfy your curiosity on this point, 

 not indeed from my own observations, 

 but by those of Professor Johann 

 Miiller, whose discoveries of the de- 

 velopments of these and kindred ani- 

 mals are among the most interesting, 

 because the most startling, of the mar- 

 vels which modern zoology has re- 

 vealed to us. The whole process is 

 ■ full of surprising details, to which the 

 change of the caterpillar to a chrysalis, 

 and that of the chrysalis to a butterfly, 

 present no parallel, wonderful as those changes of form 



LiKTA OF SEA-tTECHIir. 



